Remote engine start is prevented by passive immobilizers installed in cars on a mandatory basis in line with an UN ECE regulation. Starting a car engine is impossible without a key inside the car. On each ignition start the car's security system sends a request to the transponder which is a component of the car key, through its transceiver module (FIG. 1). The radius of interaction between the security system's transceiver module and the car key transponder varies from several centimeters to several meters (but in any case is confined to the inner space of the car). Once the interchange of correct data between the car key transponder and the transceiver module of the car's security system is completed, and the presence of the car key inside the car is verified, the operation of the car start control device is allowed, and the engine is started. Depending on the type of the key (ordinary (passive) key without its own power unit, or a “smart key” (active) with an in-built power supply) the data interchange between the key transponder and the transceiver module is effected on the carrying frequency F (120-140 kHz (ordinary key)) or on a radio frequency allowed for use, such as 434 Mhz, 868 Mhz or any other (“smart key”).
A method is available to bypass the standard in-built immobilizer for a remote engine start (i.e., with no key inside the car) based on the concept of connection to the car's critical circuits whereby an additional device (keyless bypass module) emulates the data interchanged during the transponder's identification of the car key (for instance, see Patent CA 2704810 C, Nov. 15, 2011). In other words, the start permission signals are substituted. The additional remote start device first transmits a command to bypass the immobilizer to the key bypass module which permits to start the engine (FIG. 2). Because the start permission signals are coded by the car manufacturer, a necessary condition for using such a method is the preliminary decoding of the data interchange protocol (“cracking” the interchange protocol) by re-engineering.
In that case, given the advances in security systems and coding procedures, potential compatibility of such devices with present-day cars would be reduced, since it might prove impossible to perform the decoding in a reasonably short time.
Another method of deactivating the security system is the so-called “transformer by passer” consisting of an inductive transformer one of whose coils is wrapped around the key (or its transponder) hidden inside the car, and the other is located close to the transceiver module. Such devices are widely known (for example, see http://www.mega-f.ru/common/img/uploaded/BP2-instr-0.pdf; http://lzr.ru/files/uploads/documents/instructions/immotrack/PandoraDI03.pdf; http://ultrastar.ru/attachment/37713/StarLine_BP03.pdf). Prior to a remote start the additional remote start module transmits a signal to the transformer by passer that restores the integrity of the transformer circuit thus allowing data interchange between transponder 2 and the transceiver module of the security system and enabling the engine start (FIG. 3). One obvious disadvantage of such a solution is the necessity of leaving the car key (or its transponder) inside the car resulting in the risk of the car's theft.
The closest analogue of our method is U.S. Pat. No. 8,264,320 B2 dated Sep. 11, 2012. This invention proposes to place two separate modules in the car (key storage module and remote start and key bypass module) with subsequent data interchange between them. Both aforementioned modules are controlled from an external remote start control device. Placing the car key with transponder 2 in a shielded key storage module effectively reduces the radius of its identification preventing direct communication between the transceiver module of the security system and transponder 2. All the data to be interchanged between transponder 2 and the security system's transceiver module are relayed through the remote start and key bypass module. Communication between the key storage module and the remote start and key bypass module may be carried out, inter alia, by data interchange through a wireless (radio) channel (FIG. 4).
All the known solutions for bypassing the car immobilizer reduce the security of anti-theft systems since they all require that the car key (or its transponder) be left inside the car which results in the obvious risk of the car's theft.
The task posed by the claimed invention is the development of a technical solution for bypassing a car immobilizer not depending on possible changes in the coding of data permitting a car start, and not requiring the storage of the car key (or its transponder) inside the car.
The technical result of the claimed invention would be an unconditional and safe remote start of the car engine while preserving all the original functions of the car's security system, thus expanding the spectrum of available technical tools aimed at enhancing security systems protecting against unauthorized use.